Pneumatic servo-motor



Jan. 7, E. R PRICE ETAL PNEUMATIC SERVO-MOTOR Filed Sept. 19, 1955 A Bij/, AQL? RNEY A TTO United States Patent f. .The present invention relates ,to 'a pressure `.producing device, ,and more particularly) to valco'ntrolvalve therefor. ,Devices of the abovementionedtype.usually employ control valves housed therein. ndactuated by means of a control member projecting externally of the :device I. `Devices ,of thisA type, are used inon'e application as the actuator for hydraulicbrakings'ystems of motor vehicle`sin which case the control member isusually 'pinned toa conventional foot pedal lever .whichtransm'its a 'certain amountof nonflinearmovement-t/o the control member., With. such an arrangement, the-.cohtrolmember cannot be guided with respect to the housing of the servornotor, and the control member must be connected to the control valve structure by means vof a swivel connection, adapted to permit a slight ain'ouilt of, rotational movement betweenfthe control member and the control valve structure. Sufiicient friction is ypro'dut'xed in swivel connections to transmit yawin'g forces t'o the `control valve structure, andas a result complicationsY occur. The art hasbecome highly competitive-and is ever seeking devices which are inexpensive to manufacture'and which will give longer trouble freel operation. v W t An object of the present invention is tlie'provisibnof a new and improved control valve 'structur' lfor 'pressure producingdevices and the like, eoipisiiig'thre concentri'cally arranged valve members',lthe 'center'frnember fof which is attached to one ofthe othermemb'e'rs ih ,a vmanner permitting universal movement with vrespect thereto, and theinner and outer, members of which are guided with res'pectto eachother. I

Another object ofthe invention is the 'provision of a new and improvedpnumtic servo-motorhavin'g acon; trol valve structure ofthe .above describedrv'type in which either vthe inner or outermember is swi'vll'y eduieted toand moved by a nonguided control lr'neni r, and which control valve structure is less subject to'failu-'es', and'has a V longer service life than do corresponding pi-lor art devices. v u Y m y r A further object of the invention is" lthe 'of a pneumatic servo-motor having a newfa`i1dy yifri 'ro d control valve 'structure of the above described type chfis simple in design, rugged -in construction, a'rd iiexpes'ive tomanufacture. i t t The invention resides in certain 'consti' "tions "an'deomf binations and arrangements of 'par'tsja d 4further objects and advantages will bev apparent `to 4'tho "skilleclfin the art to which the invention r't'elates fofm rthe,'folio vyii'g description of lthe preferred 'embodiment described with reference to the accompanyingdrawing for'rning a pai-t of this specilicatiomandin which: v g

Figure 1 is alongitududinal "cross sectional view .ff'a power-assisted master cylinder embodying 4the principles of the present invention; and p Figure 2 is a fragmentaryenlarged see'tional'vi'ew of the control valve of the device shown in Figure Referring' now to the drawing 'and particularly to Figure l, .the pressure producing devicshown 'thereirlfcmprises a hydraulic cylinder A positioned yon one endl of an 2 atmospheric suspended power lcylinder B, the'lat-ter living therein a movable-wall C adaptedlto operatey a@ 1d displacement member 'D which projects into the adace'i end ofthe hydraulic cylinder A, llvl'orfer'ner'it of th in able wall C is controlled by novel valve ie'ans o tioned on the movable wall vand adapted to ,"regiilate the pressure differential applied across the novble j The valve means E'is iii turn actuated by cont o l meib F which projects externlly 'of the 'povvei-"c'ylider "d which is adapted to be moved by an operators Movement of Vthe contfol'memberl into thvpower cylinder B causes the control valve E 'to close valvewG and open vacuum valve H to admit ya chamber' IV-th'er'eby causing the :piston C to f iluid displacementmembei into tlie hydraulic A to force the hydraulic fluid normally contained therein into a hydraulic system, not shown, as l'for example 'the braldngsystemof 'an"aut'voinobile.n l For a complete description of lthe constructionfaiid operatioirofrsie of the Vdtails the hydraulic cylinder A showni'n the dfawing, reference may be had to Patent N0. 2,690,740 granted to vE. E. Hupp, October 5, 19521.

The movable wall C showh'i 'the drawing is made from tyvdsections, a frontA section 10 Aand f alrear section '12 fastened together by bolts `14 so asto form a diaphragm chamber 16', as desribedliln the fabove referred to patent. The front section 10 is providedcwith an axially extending bosslshaving arrc entra l opening or valve chamber 420 therefrn in which the valve structureV E is located. An annularvalve seat'22fyis1provided adjacent the ,inner end ofthe valvechamber 2i) byslightly enlargingor counterbring the, inner endof ,theJ valve chamber 20' as at 2'4', and anannularvalve member 26 is arranged to cooperate with the seat 22.*,... f, t. v

111e annular,valvememberprtingle.15,. ,in` genera1,.a cylindricall Vsleeve shaped, member vhaving spacedapart radially/outwardly yextending flanges` 3,0,.- and The angelis `adapted vt9..'=--.bi1t.seat v22am@ the. angefu f ormsa sealwith the sidewalls :,Qffchamber `20A to\pro,vide all enclosed annular chamber ,34 whichwis supplied .with vacuumas by the flexible connection ,36. Theannular valvemembertZ'y `is adapted 4no ,bemoved axially to the right lto separatetheA inner ange..32.,-fr,om seat 22. The valvemember 26 neednot` beconstructed as .illust-rated ,but may, for example, be made froma single piece of flexible material,r suchas rubber;orthe like, or it kmay lbe made from afone-pj'ece rigidjmember, 'whoseforwardly posiL tioned flange 30s1idingly and sealingly engages thel sidewalls` 'ofthe chamberl 20. f Thepreferred construction shownin the drawing com: prisestheannular valvemember -26 made from a rigid metallic sleeve orb mainbody; portion 38, `having-aradially ,extending` rigidiangef3-2 on its v.inner lend is provided with aseating surface Y46,'of `'yieldable material; and,a, ilexible flange 30 lNon its` oute'rend. TheA radially outer portionvof ilange 3,0,is positionedin a, recess42 in thesidewall's of chamber 20a'nd is clamped 'therein as. byclampin'g plateAlj; vandftln; ra'dia'lly.l inner `nd'f thek llange) is positionedover Ta'nd bondedto 'asliglitlyI turned portion 4'6xof. ther sleeve 38.,The valve, member 2t .is heldin ,it'sryalve .closi'ngpositionz by a light coil spring ..48'ip`ositione'd` between ,thefinncr ange 32 nd -a plate 49 attachedto the inside of the frntsection 10'.` As .isflly explained in the above referred to Patent No. 2,690,740, latriosphericfpressure is always supplied to the forward chaniberl 50 'ofthe power cylinder-B,f. er., thech'mber closest to thefoperator or left ,hand'chanibe'r asviewed in thedrawing, by tubingconnec'tion S2; Passage Fof this. pressure from the .front p'oWercyli'rder 'chamber 50 to the rear powery cylinder Vcham-ber 54 through the passageway providedbythe 'central 'opening rof 'annular v-alve member 26, 'diaphragm 'chamber "16, and passage 56, is controlled by a valve closure member 58 having an annular valve seat 60therreon adapted to abut ange 30 of the annular valve member 26 and forma seat therewith. The valve closure member S shown in' the drawing comprises a cylindrical shaped portion 62 which extends through the central opening-of the annular Avalve member 26 and which has an enlarged cylindrical portion 64 on its outer end which carries the annular valve seat 60. The center of the Vvalve'closure member S8 is bored out to provide a socket 66 to receive' the ball shaped end 68 of a push rod or valve actuating member F, the other end of which is pinned to Aan automobile brake pedal or treadlo 72.

In order lto maintain the axially slidable valve closure member S8 concentric with respect to the valve member '26, two axially spaced plate members 49 and 76 are provided With central openings 82 and 80 respectively. These plate members are securely attached in any suitable manner, such as by screws 78 to the boss 18 ofthe front section 10 and insure a positive guide for the member 58 slidably received in the central openings of the plate members. Passages 84 in eachrof ther plate members 49 and 76, establish communication between chambers 50 and 54 when the valve G is in the position shown in Figure 1.

Operation i The power operated master `cylinder A is shown in Figure l of the drawing in its retracted `or non-brake applying position. In this position, 'air admitted through connection 52 is permitted to iiow from the front power cylinder chamber 50, past the valve seat 60, through the annular space between valve closure member 58 and the annular valve member 26, through diaphragm chamber 16 'and passage 56, to the rear power cylinder chamber 54. Upon depressing the pedal 72, push rod F moves valve closure member 58 inwardly to bring its annular valve seat 60 to bear against ange 30 of the annular valve member 26, as shown in Figure 2, thereby closing off latmospheric communication to the rear power cylinder cham'ber 54. Continued inward movement of valve closure member 58 forces the `annular valve member 26 lnwardly to lift 1ts inner ange 32 away from the annular ,Y Wardly of the rearwardly positioned end of said axially valve seat 22 to permit communication between the vacuum chamber 34 and the rear power cylinder chamber 54. As air is evacuated `from the rear power cylinder chamber 54, the movable wall C is forced inwardly by the differential pressure thereacross. If the operator holds the push rod F in one position, the movable Wall C carries the annular valve seat 22 inwardly to abut ange 32 of the 4annular valve member 26. In this position, the valve scat 60 -of the valve closure 58 still abuts ange 30 of the annular Valve member 26 and Xa lapped position of both valvesfis reached. In this position of equilibrium, air will neither be owing in nor out of the rear power cylinder chamber 54, and the uid displacement member D will have forced a predetermined 'amount of brake iiuid into the braking system of the vehicle. If more braking force is required, the brake pedal may be further depressed to cause more brake liuid to be forced into the braking system of the vehicle; and if less braking effort is required, the pedal may be partially retracted, until a new lapped position of the valve structure is assumed, all in a manner well known in the art.

lIt will be seen that the objects heretofore enumerated as well as others have 'been accomplished, and that there has been provided a new and improved control valve structure for a pneumatic powered master cylinder and the like comprising three concentrically arranged valve members, the center member yof which is attached to one of the other members in a manner permitting universal movement with respect thereto, and the inner and outer members of which are guided with respect to each other; such that the valve members automatically and correctly position themselves with respect to each other, even though they are actuated by. a non-guided control member.

While the preferred embodiment ofthe invention has been described in considerable detail, we do not wish to be limited to the particular construction shown which may be varied within the scope of the invention, and it is the intention to cover hereby all adaptations, modiiications and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

We claim:

l. A pneumatic liuid pressure servo-motor comprising a power chamber, a movable wall in said power chamber, an axially extending valve chamber in said movable wall, a iirst coaxially positioned annular valve seat facing rearwardly of the rearwardlypositoned end of said axially extending chamber, a first axially movable generally tubular valve member in said axially extending valve chamber having generally radially outwardly extending flange portions adjacent its opposite ends, one of said flange portions being rearwardly positioned from land adapted and arranged to overlie and close oi said first annular valve seat, and the other of said flange portions being a tiexible member the radially outer edges of which are rigidly supported by the walls of said valve chamber to form an enclosed chamber, 'a second valve member having a first portion projecting valve seat on said enlarged portion of said second valve member adapted and arranged to abut the forward flange of said rst tubular valve member and form a seal therewith, a control member projecting into said servo-motor and swivelly connected to said second valve member, rst means guiding said first portion of said second valve member for axial movement, and second means guiding said enlarged portion of said second valve member, said first yand second means being supported by the movable wall and being spaced on opposite ends of said rst valve member.

2. A pneumatic liuid pressure servo-motor comprising a power chamber, a movable wall in said power chamber, an axially extending valve chamber in said movable wall, a first coaxially positioned annular valve seat facing rearextending chamber, a rst axially movable tubular valve member in said axially yextending valve chamber having generally radially outwardly extending flange portions adjacent its rearwardly and forwardly positioned ends, the rearwardly positioned iiange portion of said valve member being positioned rearwardly of and constructed and arranged to overlie` and close ol said first annular valve seat, and the forwardly positioned llange portion of said v valve member being a diaphragm the outer edges of I valve member zand having an enlarged portion positioned which are rigidly supported by the walls of said valve chamber to form a-n enclosed chamber, a second axially positioned valve member having a portion projecting through the axially extending opening of said first tubular forwardly of the `forward flange of said tirst tubular valve member, a second rearwardly facing annular valve seat on said enlarged portion of said second valve member constructed and arranged to abut the forward llange of said rst valve member and form a seal therewith, a control member projecting into said servo-motor and swivelly connected to said second valve member, first means guiding the rearwardly positioned end of said second valve member for axial movement, and second means guiding the enlarged portion of said second valve member for axial movement, said iirst and second means being supported by the movable wall and being spaced on opposite ends of said first valve member.

3. yA pneumatic uid pressure servo-motor comprising a power chamber, a movable wall in said power chamber, an axially extending valve chamber in said vmovable wall, a trst coaxially positioned annular valve seat facing rearwardly from the rearwardly positioned endy of 5 said axially extending chamber, a lirst axially movable tubular valve member in said axially extending valve chamber having generally radially outwardly extending flange portions adjacent its rearwardly and forwardly positioned ends, the rearwardly positioned ilange portion of said valve member being positioned rearwardly of and constructed and arranged to overlie and close oi said iirst annular valve seat, and the forwardly positioned ange portion of said valve member being 'a diaphragm the outer edges of which are clamped to the walls of said valve chamber to form an enclosed chamber, a second valve member having a iirst generally cylindrical portion projecting through the axially extending opening of said first tubular valve member and having an enlarged generally cylindrical portion positioned forwardly of the forward flange of said rst tubular valve member, a second rearwardly projecting annular valve seat on said enlarged portion of said second valve member constructed and arranged to abut the forwardly positioned 'ange of said irst valve member and form a seal therewith, a control member projecting into said servo-motor and swivelly connected to said second valve member, a first guide plate connected to said movable wall and having a hole therein adapted to receive the rst generally cylindrical portion of said second valve member, and a second Iguide plate connected to said movable wall and having a hole therein adapted to receive the enlarged generally cylindrical portion of said second valve member.

References Cited in the tile of this patent UNITED STATES PATENTS 1,927,942 Lobez et al Sept. 26, 1933 2,331,238 Schnell Oct. 5, 1938 2,421,726 Thomas lune 3, 1947 2,735,268 Stelzer Feb. 21, 1951 

